JPH0624320A - Lock prevention adjusting device for automobile - Google Patents

Abstract

PURPOSE: To achieve an optimal pressure build-up function in an antilock control system for a motor vehicle and maintain the advantage of a pressure at the optimal point for a long periods of time and thus achieve better brake deceleration with greater stability of travel and greater comfort than those of a conventional antilock control system. CONSTITUTION: In addition to an antilock controller 3 as a monitoring circuit. a pressure function generator 4 is provided and, whenever wheel overbraking is detected, the pressure function generator 4 stores intermediately stores a brake pressure value for each wheel. Then, the pressure function generator 4 gives off a signal to a pressure modulator 1 in a pressure holding stage in order to increase the wheel brake pressure in accordance with an exponential function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel sensor, a monitoring circuit for detecting a wheel overbraking state from a signal of the wheel sensor to generate a control signal, and a pressure for setting a wheel control pressure by the control signal. The present invention relates to a lock prevention adjusting device for a vehicle, which includes a modulator.

[0002]

2. Description of the Related Art In addition to determining an appropriate switching time point, it is also possible to know a reference pressure point in a typical antilock adjustment step, that is, when periodically switching between pressure reduction, pressure holding and pressure establishment. ， It is extremely important to obtain a large uniform vehicle deceleration with the most comfortable braking. Assuming a uniform braking condition, and assuming that the properties of the tire and brake do not change during braking, set a braking pressure that is lower than the locking pressure by a value that is different from the locking pressure for each wheel that may be locked. As a result, the lock prevention device can perform optimum braking. This pressure can be stored for each wheel when a locking tendency occurs for the first time during braking. After eliminating the locking tendency, the maximum deceleration, by the optimum pressure set at a place slightly lower than the locking pressure,
Braking can be ended with good driving stability and high adjustment comfort. However, if the wheel still has a tendency to lock after setting a constant pressure, the setting process will be reversed based on the new lock pressure.

However, one should not actually use this simple strategy. This is because the wheel lock pressure may fluctuate significantly for the following reasons. First of all, even if almost all actual braking is carried out on homogeneous ground conditions, locally very large local friction coefficient fluctuations occur. In addition, the dynamic behavior of the vehicle causes a change in the wheel ground contact force (especially due to a load change caused by a curved path or a deflection of the vehicle due to a change in deceleration at the start of braking). During braking from a high initial speed, the characteristics of the tire change strongly due to warm skin rise.
During long braking, the braking system exhibits a damping effect, which results in either a constant braking pressure which is set or a braking pressure which decreases with time.

Therefore, for reliable regulated braking, the braking pressure on each wheel that rotates in a stable slip range is increased again to reach the parent braking cylinder pressure desired by the driver in extreme cases. It is absolutely necessary.

Further, since the change in the wheel ground contact force due to the jumping of the wheel causes a dynamic change in the rock pressure, after the rock tendency tends to disappear, the pressure is returned to near the previous rock pressure at an arbitrary speed. It is not allowed to change.

[0006]

Therefore, the object of the present invention is to have an optimum pressure establishing function, to substantially maintain the advantage of pressure holding at the optimum point over a long time range, and thus to obtain great running stability. It is an object of the present invention to provide an anti-lock adjusting device of the type mentioned first, which achieves better braking and deceleration than the conventional anti-lock adjusting device with high adjustment comfort.

[0007]

In order to solve this problem, according to the present invention, in order to improve comfort and shorten the braking distance, a pressure function generator is provided in addition to the monitoring circuit, and wheel overbraking is provided. Whenever a pressure is detected, the pressure function generator temporarily stores the braking pressure for each wheel, stores it as the upper reference point Pein, and the lower reference at which the wheel accelerates again the braking pressure reduced by the pressure modulator. Stored as the point Pbeschl, and subsequently during the pressure establishment phase, the pressure function generator signals the pressure modulator to increase the wheel braking pressure exponentially between the upper and lower reference points.

[0008]

The anti-lock adjusting device according to the present invention does not perform pressure establishment in the re-pressurizing stage with a constant gradient, but changes the braking pressure more and more rapidly, and when the expected rock pressure is almost reached. ， Then the braking pressure changes gradually. By using such an exponential pressure curve, good pressure levels are obtained quickly and are maintained for long periods on homogeneous ground.

The expected drop in wheel speed at the end of the pressurization curve is generally mild and can easily be eliminated due to the gentle final slope of the exponential pressurization curve.

The basic condition for the success of this pressure-raising mechanism is to obtain a pressure function between good pressure reference points.

It is assumed here that the anti-lock regulator (ABS regulator) can use the information about the pressure present in the wheel braking circuit. Here, only the pressure relationship is required, not the absolute pressure. Plunger pressure modulator (eg German Patent Application Publication No. 353028)
The high cost of the braking pressure generator is simply avoided by the use of (see No. 0).

[0012]

EXAMPLES The present invention will be described below with reference to examples.

The meanings of variables and constants used here are as follows. S = signal of the wheel sensor which makes it possible to determine the actual peripheral speed V of the wheel V = instantaneous peripheral speed of the wheel A = filtered wheel deceleration or acceleration VREF = calculated vehicle reference speed (filtered wheel AREF = filtered vehicle deceleration or temporal derivative of VRE (vehicle deceleration that is evaluated but very strongly fluctuates due to the short adjustment time; hence this signal in general). AREF is assumed to be such filtered vehicle deceleration. RE = Wheel speed dip indication signal (set to logic "1" when wheel speed enters too large a slip range due to overbraking). When the actual wheel slip is stable, logic "0"
"Becomes a Boolean 1 bit signal" DeltaVhalt = time DeltaThalt
Difference in speed taken by the wheel DeltaThalt = Duration of pressure holding stage during acceleration of the wheel to a stable slip. The time when the pressure holding phase starts at the second time and thus accelerates the previously over-braked wheel. Taus_i = The time when the wheel speed drop disappears at the i-th time during the adjustment braking TS = The start time of the trial pressurization TPAuf = The wheel lock tendency returns again Allowable duration of expected pressure buildup P = Wheel braking pressure (this pressure is ABS during controlled braking)
Set by the regulator. That is, the mechanism envisioned here indirectly affects P via the ABS regulator).
The concept envisaged here assumes that P is sensed by a pressure gauge, or if, for example, an anti-lock pressure modulator according to the Plunger principle is used, it is relative to the measurable position of the front wheel pressure plunger. It is assumed that there is a direct relationship with the front wheel braking pressure and thus P can be read as a relative quantity from the respective plunger position. Palt = Wheel braking pressure P PS of the preceding regulation cycle P PS = Target value of the braking pressure to be set (calculated by the pressure function generator in the pressure establishment phase and given to the ABS regulator) PSneu = For the next regulation cycle New value of PS for Pein = value of P at which the wheel has a tendency to rock Pein_i = value of P at which the front wheel speed drops at the i-th time during adjusted braking pressure Pbeschl = value of P at which the wheel that previously dropped down accelerates again PSAnf = re-addition Pressurization start point as starting pressure point of pressure curve DPSAnf = P based on wheel, axle and vehicle motion
Minimum distance from SAnf to Pein DeltaPAuf = pressure value of the wheel braking pressure which is increased in the repressurization phase from one adjustment cycle to the next adjustment cycle DeltaPMin = from one adjustment cycle to the next adjustment cycle At least in the repressurization step Pressure value of increased wheel braking pressure DeltaPMax = pressure difference between Pein and Pbeschl. If this pressure difference is exceeded, the pressurization start point PSAnf is calculated based on Pbeschl. Pab = wheel braking pressure included when the HBZ valve (plunger pressure modulator) is closed K1, K2 = Calculate braking pressure function Constant z = Plunger position to be set (plunger pressure modulator) Adjustment cycle clock = Clock signal that can be switched by duration of lock prevention adjustment cycle (here 8 ms): 125 Hz 1 g = Gravity acceleration = 9.81 m / s ^Two

FIG. 1 shows an electro-mechanical-hydraulic-pressure modulator 1
2 shows a block diagram of a lock prevention adjusting device consisting of an electronic control unit 2 and an electronic control unit 2. The electronic control unit 2 performs adjustment in addition to the elements for the ABS adjuster 3 and therefore an auxiliary circuit 4 called a pressure function generator. Is included. The function blocks 3 and 4 can be realized by special hardware or software.

For clarity, "the mechanism shown here is only intended for wheels or braking channels, so the figures show only one channel element.

Extensions to n-channels are readily possible because there are no inter-relationships affecting the channels and thus the mechanism can be considered separately for each wheel or each braking channel.

Data or signals specific to the wheel or braking channel must be given appropriate subscripts when extended to multiple channels, but again these indices have been omitted for clarity.

In order to show the inclusion of the pressure function generator in a conventional anti-lock regulator, only the functional relationships of blocks 1, 3 and 4 will be described below. The ABS regulator 3 receives the pulse train S from the wheel sensor 5 and calculates the actual peripheral speed V of the wheel from the number of turns of this pulse train. From this peripheral speed V to AB
The S adjuster 3 can determine another internal reference signal, such as the vehicle reference speed VREF and the vehicle reference deceleration AREF, thereby detecting an overbraking condition and eliminating it. When the adjustment is started, the ABS adjuster 3 gives a pressure control signal to the pressure modulator 1. Therefore, this pressure modulator decreases the parent braking cylinder pressure PHBZ defined by the driver to obtain the braking pressure P of the wheel braking cylinders. Send to the wheel braking circuit. The pressure modulator 1 provides a response signal to the ABS regulator 3. These response signals contain information about the braking pressure P to be set, and thus in the case of a plunger pressure modulator (eg German Federal Republic of Germany DE 35 30 280),
This is the position that determines the plungeer pressure.

The internal reference signal can be used together by the pressure function generator 4.

The ABS adjuster provides anti-lock adjustment as is well known. In parallel with this, the pressure function generator 4 calculates the slope of the optimum repressurization curve in the pressure establishment stage and feeds it to the ABS regulator, which ABS data is the data of the pressure function generator. Basic adjustments can be improved.

Accordingly, the ABS regulator and the pressure function generator operate in parallel. The basic function of the ABS regulator is known and will not be described further. In practice, the ABS regulator 3 and the pressure function generator 4 can be regarded as one element. Here the logical separation is only done to clarify the function of the pressure function generator.

The anti-lock adjusting device actually used according to the prior art periodically switches the adjusting states of pressure reduction, pressure holding and pressure establishment in each wheel. In this regard, FIG. 2 shows an example of the lock prevention adjustment on a homogeneous road surface. Whenever the wheel is slipping high enough to exceed the maximum permissible deceleration value, the pressure reduction takes place normally.
This state exists at the time point Tein_i (i = 1, 2 ...
・ ・). As the wheel transitions from the preceding deceleration phase to the acceleration phase and thus again rotates in the stable slip range, the resulting pressure holding takes place, which occurs at time Thalt_i. When the wheel turns again with a stable and stable slip, the pressure is reestablished (time point Taus_i), in most cases for the first time only a relatively large pressure jump is made, and then a continuous pressure establishment with a constant gradient takes place. (Hereinafter, this is referred to as a pressure establishing stage or a repressurizing stage), and the wheel speed drop again forced by it causes the pressure reducing stage again. If such a velocity drop does not occur within the fixedly established pressure establishment time TPAuf, trial pressurization is performed with a steeper pressurization curve, and the set pressure is less than the maximum possible value. Not too far apart (trial pressurization begins at time TS).

Since overbraking of the wheels is always caused after a certain pressure is established, exceeding the maximum value of the friction coefficient-slip curve is unavoidable. The more the wheel enters into unstable slip, the smaller the wheel drive by the road, so the positive feedback increases the tendency of the wheel lock, and thus a stronger pressure reduction is needed to eliminate the wheel lock again. Strong pressure modulation has an unpleasant effect, especially on motorcycles, putting a load on the axle mechanism and practically always reducing vehicle deceleration.

FIG. 3 shows a time diagram of the wheel braking pressure, which shows the wheel speed and the pressure establishing function for the adjusted braking. This pressure establishment function is generated by the mechanism described below.

Memorization of Wheel Lock Pressure When the ABS regulator detects that there is a tendency for wheel lock due to overbraking, the pressure establishment stage ends and the pressure reduction stage is switched to. At this point, the ABS regulator sends the signal RE
Is switched from logic "0" to "1" (wheel speed drop). The wheel braking pressure (or the piston position in the corresponding channel) is now registered in the register by the wheel lock pressure Pei.
stored as n. For subsequent adjustments it is possible to start on the assumption that this pressure point is slightly too high on a homogeneous ground.

Pressure Decrease with Minimum Gradient Proportional to Speed When overbraking of the wheel is detected, there is a pressure reduction in each adjustment cycle by a value calculated proportional to the wheel speed gradient. Therefore, if there is a strong tendency to lock the wheels, it will be reduced more strongly than if the slip range is gradually increased. However, in order to stop the expected positive feedback effect, there is always a fixed minimum pressure reduction even when the wheel enters a very unstable and unstable sliding range. It is assumed that the pressure function generator 4 does not do this because the ABS regulator itself does such a pressure reduction.

Memory of Wheel Acceleration Pressure The pressure reduction phase is carried out until the wheel entering a too large slip range is again surely accelerated. At this point the pressure holding phase begins and the ABS regulator holds the resulting braking pressure constant. If the measured vehicle deceleration is very small and from this the low coefficient of friction of the ground is inferred, the ABS regulator will intentionally place the pressure holding point slightly lower, which will cause the wheels to accelerate better and It can rotate in an unstable slip range for a short time, which is especially important for motorcycles with anti-lock adjustment.

Furthermore, the ABS regulator constantly monitors wheel speed changes during the pressure holding phase. If the acceleration in steady slip is too low, the ABS regulator will reduce the holding pressure a little more. If the wheel acceleration increases too strongly, the ABS regulator will make less pressure build up accordingly.

If a transition to a smaller coefficient of friction occurs during the pressure holding phase, and the wheel decelerates to a larger and more unstable slip, the ABS regulator then starts the pressure reduction phase again and this pressure reduction occurs again during wheel acceleration. Following the step, the pressure holding step is carried out again.

All of these actions of the ABS regulator thus bring the wheel into a stable resting slip in an acceptable time range.

Importantly, the ABS regulator brings the wheel back into a stable slip and brings this to a logical "1" to "0".
The pressure function generator 4 takes over the wheel braking pressure (or the pressure piston position of the wheel braking channel) as the acceleration pressure Pbeschl at the time indicated by the reset of the signal RE to (FIG. 3).

In a homogeneous immediate surface state, this pressure Pbesc
hl is too low for subsequent adjustments and will always be exceeded during the pressure building stage.

Calculation of a good starting point for pressure application At the end of the pressure holding phase, when the wheel is once again in the stable slip range, the pressure establishment phase begins. The ABS regulator detects this condition by various criteria. In order to ensure that the braking pressure that is set is at the optimum value for the longest possible time, a positive pressure jump is first attempted, which initiates an exponential repressurization at an already good pressure level. The pressure start point obtained by the pressure jump is referred to herein as the pressurization start point. But of great importance to the quality of adjustment is that pressure jumps do not immediately lead to overbraking of the wheels, because of the frequent establishment of large values of pressure and the instability of the vehicle caused by the pressure. is there. This erratic behavior of the vehicle
It appears as a steering wheel shimmy in passenger cars.
Motorcycles with soft front wheel suspensions are prone to capsize (rear wheel levitation) and so-called jumping horses. In order to avoid this phenomenon, the pressurization start point PSAnf is set to the previously stored lock pressure Pein and wheel acceleration pressure Pb.
Calculated from eschl and further limited in view of the nature of the vehicle, each type of wheel undergoes different treatments with respect to its axle characteristics and the class of tire used.

To calculate the pressurization starting point, first the arithmetic mean value of the lock pressure and the wheel acceleration pressure is formed. PSAnf = (Pein + Pbeschl) / 2

When a large pressure value is required at first to eliminate the wheel locking tendency (Pein-Pbeschl).
> DeltaPMax), the pressure jump does not take place to both of these stored reference pressure points, and the basic value Pbesc
Starting from hl, the jump height is calculated from the wheel acceleration in the pressure holding phase. PSAnf = Pbeschl + Kl * DeltaVha
lt / DeltaThalt

This second function is important if the wheel overbraking, which was previously eliminated, is caused by a shift in the friction coefficient to a lower value. In this case, the pressure holding point should be regarded as the basic value for the next repressurization. The effective pressure jump then consists only of terms (related to wheel speed) that take into account the braking torque deficit present during the pressure holding phase. The stronger the wheel is accelerated in the pressure holding stage, the larger the pressure jump to be added to Pein.

In order to prevent jumps from producing too high pressure values, especially on the front wheels, when the load changes too large, further vehicle-specific boundary conditions must be maintained. PSAnf ≦ Pein−DPSAnf where DPSAnf = f1 (VREF) + f2 (ARE
F)

The functions f1 and f2 result from the test measurement sequence,
Very specific to the vehicle. In principle, the rule holds that a pressure decrease to eliminate overbraking of a wheel causes a load change that increases with the strength of the vehicle deceleration. This load change mainly results from jumping of the front axle. Therefore, the more the vehicle decelerates, the less the front wheels are subsequently loaded. On smooth terrain, pressure modulation of the front wheels causes only small load changes, so even if a wheel is pressure-reduced before and then rotates in a stable sliding range, it may be just below the front rock pressure. Good braking pressure can be applied. This is because the decrease in ground contact force did not occur due to the decrease in pressure. This effect is especially noticeable in motorcycles. In this case, a strong pressure increase causes a significant jump of the front wheel fork. Correspondingly, a strong front wheel pressure reduction causes a rapid front wheel fork jump, the reduction of the wheel contact force being significantly greater in a short period of time than would be expected due to relative center of gravity shifts (eg See German Patent Application No. 4204350.6).

The opposite effect occurs at the rear wheels. The decrease in pressure reduces the vehicle deceleration, which increases the possibility of pressurization due to the wheel ground force. Therefore, in this case the pressure point after the wheel locking tendency has been eliminated may be just below the previous locking pressure.
This is especially true for motorcycles when only the rear wheels are braked. This is because, in this case, only the rear wheel pressure modulation / modulation is important for the fluctuation of the wheel contact force.

As the vehicle speed increases, the pressurization start point can be made higher (just below the lock pressure). At that time, the operation of the tire plays an important role.

FIG. 4 shows the maximum pressure value for the front wheels as an example. By lowering the pressurization starting point PSAnf, it is possible to ensure that the immediately following locking condition (as shown in FIG. 2) practically no longer occurs on homogeneous ground.

Exponential pressure establishment function From the pressurization start point PSAnf obtained after the jump, to the previously recognized lock pressure point Pein, pressurization is performed according to the exponential pressurization curve. The slope of the curve is initially large and then the previous rock pressure point Pei
It gradually becomes gradual as it approaches n. Thus, for each pressure increase from one regulating cycle to the next, the following equation is obtained: DeltaPAuf = K2 * (Pein-PS) where K2 << 1 The new braking pressure target value is the same as the previous value.
It can be easily obtained by increasing by f. PSneu = PS + DeltaPAuf

By each adjustment cycle, the braking pressure PS is Pe
By increasing the pressure closer to in, the pressure increase by the above equation becomes smaller and smaller. It is particularly easy to implement such a function in a microcomputer by choosing square as the function. It has actually been found that a value of 1/8 is better with an adjustment cycle time of 8 ms. DeltaPAuf = (Pein-PS) / 8

In order for the pressure to actually reach the lock pressure and for the pressure curve to asymptotically extend to this pressure, the following minimum gradient is required. The value of DeltaPAuf ≧ DeltaPMin DeltaPMin must be set specifically for the vehicle and the wheels. It should be further noted that the size of DeltaPMin is chosen so that the re-pressurization curve always produces a light wheel locking tendency after about 300 ms. Exponential pressurization curves allow high pressure levels to be obtained quickly. Furthermore, by this, the pressure starting point PS by the function of FIG.
The Anf can be placed relatively low so that the pressure curve that follows is not too low.

All pressure values and pressure difference values in the above equations are relative values, ie it is not necessary to know the absolute value of the pressure in order to specifically carry out the adjustment algorithm. All that is important is that the pressure curve shown in FIG. 3 extends in the correct relationship, which can be done by the plunger pressure modulator described below without the expense of measuring the position of the plasticizer.

Possibility of Plunger Principle In the lock prevention device that operates based on the plunge principle,
The wheel braking pressure can be set via the position adjustment of the plunger. When the position of the plunger is determined by the position measuring device, the ABS regulator always has information on the relative pressures available.

FIG. 5 shows the operating principle for the wheels. Parent braking cylinder H generated by the driver during regular braking
The pressure in BZ directly reaches the circuit of the wheel braking cylinder RBZ. When overbraking is detected, the ABS regulator controls the engine indexing force MF, so that the pressure piston DK resists against the force FF of the compression spring via the lever and by the force PF of the internal pressure acting on the piston. , The piston is moved in the direction of increasing z. Ball valve K with slight piston movement
As V closes, the wheel braking cylinder pressure is decoupled from the parent braking cylinder pressure and the pressure Pab is trapped in the wheel tendency circuit. The larger the piston moves in the direction of the stroke z, the more strongly the pressure decreases due to the resilience of the braking system. Starting from the trapped pressure Pab, there is a pressure function that decreases to zero over stroke z,
This pressure function changes linearly or slightly gradually depending on the braking system. The compressive force FF of the spring is the active reaction force PF and MF.
By reducing the engine indexing force MF so that the sum of the above and the passive frictional force of the braking system is again exceeded, the pressure is established again by the movement of the piston in the direction of decreasing the z value. The stroke position obtained directly indicates the braking pressure with respect to the pressure Pab via the pressure-stroke function which is subsequently applied.

If the ball valve KV remains closed, there is a unique relationship between the piston stroke z and the braking pressure P. It is thus possible to replace all previously used pressure values by, for example, the line extent z indicated by the induction position measuring coil WMS. That is, all the values of the pressure difference (pressure decrease gradient and pressure establishment gradient) are changed according to the stroke. Due to its analog nature, the plunger pressure modulator can precisely follow the fine stroke or pressure curve according to FIG.

FIG. 6 shows an implementation according to the invention.
When the ABS regulator switches the signal RE from logic "0" to "1", thereby indicating that a wheel locking tendency has been detected, the pressure function generator 4 stores the wheel braking pressure Palt by means of the register 6. . By adjusting the braking pressure of the ABS adjuster, the wheel enters stable slip again, and the ABS
When the regulator resets the signal RE to "0" again, the register 7 triggered by the negative clock pulse edge assumes the wheel braking pressure Palt as the reference pressure Pbeschl point.

To calculate the pressurization starting point PSAnf,
Two different methods are performed. That is, the adder 14 and the divider 15 form the average value of both reference pressures Pein and Pbeschl in order to form the pressurization start point PSAnf. Instead, the elements 16 to 21 have a pressure holding value Pbe.
PS consisting of the sum of schl and terms related to wheel acceleration
Calculate the value of Anf. In order to determine the wheel acceleration during the pressure holding phase, the register 17 holds the wheel speed V when the wheel is surely accelerating again. Comparator 1 to do this
6 compares the wheel acceleration A with 0, and gives a positive clock pulse side to the register at the time of switching from wheel deceleration to wheel acceleration (wheel acceleration A changes from a positive value to a negative value). At the same time, when the pulse side reaches the reset input terminal R of the holding stage counter 19, this counter 19 becomes zero.
Is set. In each successive adjusting cycle, the adjusting cycle clock pulse is applied to the clock input of the counter, so that the counting state of this counter 19 is increased by one. The subtractor 18 calculates the wheel speed V actually obtained.
And the speed VMin stored in the register 17 is always formed. The difference DeltaVhalt, and thus the value of the wheel acceleration again, is divided in the divider 20 by the counting state of the counter 19 and thus the duration of the pressure holding phase,
The multiplier 21 further multiplies the normalization coefficient K1. The pressure component calculated in this manner is added to the holding pressure Pbeschl by the adder 22. As mentioned above, one of both calculation methods is chosen for the formation of the pressure starting point PSAnf. Lock pressure Pein and holding pressure Pbesc
If the difference from hl is smaller than DeltaPMax, the first
The calculation method of is selected. Therefore, the subtractor 12 is Pein
And Pbeschl are formed, and this difference is the value Delta
The comparator 13 checks whether the aPMax is exceeded. When this difference falls below DeltaPMax, the comparator 1
Since 3 gives a logic "0" to the multiplexer 28, the value of the first calculation method reaches the minimum value former 29.

This minimum value generator 29 checks whether the calculated value is too large for PSAnf. The elements 23 to 27 according to FIG. 4 thus form a minimum function of PSAnf whose calculated value must not be exceeded for vehicle dynamics reasons. The function blocks 23 and 24 respectively calculate pressure components in relation to the vehicle reference speed VREF and the vehicle reference deceleration AREF, and these pressure components are first calculated by the adder 2
5 and the subtractor 26 adds the lock pressure Pei.
is subtracted from n. When this value is larger than the holding pressure Pbeschl, the holding pressure Pbeschl itself is output. Finally, the minimum value former 29 limits the value calculated for PSAnf to the maximum value formed by the maximum value former 27. The monoflop 30 triggered by the negative pulse side of the signal RE produces a positive pulse applied to the multiplexer 31 for about 1,5 adjustment cycles, and this PSAnf is thus fed to the data input of the register 32. Therefore, at the beginning of the pressure establishment stage, P
The final value of SAnf is passed to register 32. This value is passed to the register 32 as the pressurization curve function value PS by the next positive pulse side of the adjustment cycle clock pulse. The pulse length of the monoflop 30 is chosen so that the final value of PSAnf actually exists at the time of delivery.

The stored lock pressure Pein and the braking pressure target value PS obtained in the preceding adjustment cycle
The pressure function generator forms the subsequent pressurization curve by means of the elements 8 to 11 by means of the subtractor 8 always calculating the difference between and. The multiplier 9 multiplies this difference by a fixed number K2, and sends the minimum pressure value DeltaPMi through the maximum value generator 10.
Limited to n. The value DeltaPAuf, which is obtained from this and is to be increased during the actual adjustment cycle, is added to the pressure target value PS actually stored in the register 32 by the adder 11 to obtain the next positive value of the adjustment cycle clock pulse. It is stored as a new value of the pressure target value PS by the pulse side of. Because the disappearance of the pulses on the monoflop 30, the multiplexer 31 now connects the upper channel to the register 32.

During the pressure establishment stage (RE = logic “0”), A
The BS regulator has only the role of receiving the target pressure value PS and setting it by the pressure modulator.

By calculation of a pressure-dependent function which varies according to an exponential function and is suitable for the vehicle, it has been found in fact that the regulated braking is significantly improved over the linear pressure variation used hitherto. The short-lasting rock state of FIG. 2, which causes a significant dip in riding comfort and braking deceleration, especially in motorcycles with high-power wheels and axles, is a well-selected addition before the start of the exponential pressure curve. Pressure start point PS
By giving Anf according to the above equation, it can be practically completely avoided on homogeneous ground.

[Brief description of drawings]

FIG. 1 is a block diagram of a lock prevention adjusting device according to the present invention.

FIG. 2 is a diagram showing an adjusted braking process with anti-lock adjustment with respect to time.

FIG. 3 is a diagram showing a pressure memory point and a pressure establishment process with respect to time.

FIG. 4 is a diagram showing a function for obtaining a maximum pressurization start point.

FIG. 5 is a diagram showing the structure of a one-channel plunger pressure modulator together with a piston stroke.

FIG. 6 is a block diagram of a pressure function generator.

[Explanation of symbols]

 1 Pressure Modulator 3 Monitoring Circuit (ABS Regulator) 4 Pressure Function Generator 5 Wheel Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Georg Lol Heisenschuttam Hegerschutrace 2 of the Federal Republic of Germany 2 (72) Inventor Heinz-Eff Ohm Federal Republic of Germany Vuitersutt Franz-Serigel Schutrase 8

Claims (9)

[Claims] 1. A wheel sensor comprising: a wheel sensor; a monitoring circuit for detecting a wheel overbraking state from a signal of the sensor to generate a control signal; and a pressure modulator for setting a wheel braking pressure by the control signal. In order to improve comfort and shorten the braking distance, a pressure function generator (4) is provided in addition to the monitoring circuit (3), and the pressure function generation weak (4 ) Temporarily stores the braking pressure for each wheel as the upper reference point Pein and the braking pressure reduced by the pressure modulator as the lower reference point Pbeschl at which the wheel accelerates again, and subsequently establishes the pressure. Lock prevention for motor vehicles, characterized in that the pressure function generator (4) gives a signal to the pressure modulator in a stepwise manner to increase the wheel braking pressure according to an exponential function between the upper reference point and the lower reference point. Adjustment device. 2. When the difference between the upper reference point and the lower reference point is large, and thus a strong pressure reduction is required to eliminate the tendency of the preceding wheel lock, the lower reference point Pbeschl extends exponentially. The anti-lock adjusting device according to claim 1, wherein the anti-lock adjusting device is used as a starting point PSAnf of a curve. 3. A large wheel acceleration occurs when the difference between the upper reference point and the lower reference point is large, and thus a strong pressure reduction is required to eliminate the tendency of the preceding wheel lock, and during the pressure holding stage. In this case, the starting point PSAnf of the exponentially extending pressurization curve is formed from the sum of the lower reference point and the term relating to wheel acceleration, and the term relating to wheel acceleration is the average wheel acceleration in the pressure holding stage. The anti-lock adjusting device according to claim 1, wherein the anti-lock adjusting device is formed by multiplication with a constant coefficient. 4. The starting point of the exponentially extending pressurization curve when the difference between the upper and lower reference points is small and therefore only a weak pressure reduction is required to eliminate the preceding wheel locking tendency. The PSAnf is formed as an arithmetic mean value of the upper control point and the lower control point, and
The lock prevention adjusting device described in. 5. The starting point P of the exponentially extending pressure curve.
5. The anti-lock adjusting device according to claim 1, wherein SAnf is limited to a maximum value which is formed by decreasing a certain pressure value from the upper reference point Pein. 6. The constant pressure value is replaced by a value relating to the vehicle speed, which value decreases with increasing vehicle speed, so that at high speeds a high starting point PSAnf results. The lock prevention adjusting device according to claim 5. 7. A value related to vehicle deceleration is further added to a value related to vehicle speed, this value increasing with increasing deceleration, and thus a lower starting point PSAnf at higher deceleration.
7. The anti-lock adjusting device according to claim 6, wherein: 8. The method according to claim 1, characterized in that the exponentially extending pressure curve is limited to a minimum slope, whereby the upper reference point is not only asymptotically obtained, but also exceeded after the final time. 7. The lock prevention adjusting device according to any one of 1 to 7. 9. A pressure-function generator (4) is provided in software in the anti-lock controller as a component of the anti-lock regulator, in one of claims 1 to 8. Lock prevention adjustment device.